Clark on what he is most proud of: “I helped identify the chemical behavior of plutonium in contaminated soils and concretes at the Rocky Flats Environmental Technology Site. Good scientific understanding in the public interest helped bring clarity and focus to real issues of plutonium migration at the site. This, in turn, allowed the most extensive cleanup in the history of Superfund legislation to finish a year ahead of schedule, ultimately resulting in billions of dollars in taxpayer savings.”

What his colleagues say: “Clark has made seminal contributions in synthesis, spectroscopy, chemical reactivity, environmental behavior, and electronic structure of actinide complexes. Simultaneously, he has provided scientific insight and leadership in nuclear areas of critical importance to the nation.”—William J. Evans, University of California, Irvine